[RE-wrenches] Midnite AIO Generator Functionality

Ray Walters ray at solarray.com
Mon May 12 10:11:30 PDT 2025 

So the bypass switch gets the house power on, and I too always recommend 
a hard bypass switch. However, you still need a 48 v power supply to get 
the battery system back up, and that's becoming a serious pain in my 
aging backside.  Until AIOs with Li+ batteries, lead acid would have 
enough voltage to get the charge controller to come back on, and 
eventually the customer could get the inverter back on too.  No special 
trip out.

We need an independent circuit that would sense array voltage, and wake 
up the battery, so it could take a charge: a backup battery for the 
offgrid battery.  Without that, AIOs and Li+ batteries are not self 
healing like Lead Acid.  We are going backwards fast, but with an 
amazing amount of new Chinese technology driving the jalopy in reverse.  
(Danger Will Robinson)

Ray Walters
Remote Solar

On 5/12/2025 10:54 AM, Jason Szumlanski via RE-wrenches wrote:
> We always recommend a transfer switch to bypass the inverter and send 
> generator power to the loads. Most clients take us up on it. For 
> retrofits, sometimes there can be space limitations, however.
>
> As for the function of the AIO, there is no integrated mechanical 
> bypass, and since there is an internal relay controlling the 
> generator input (or smart load output on that breaker), I think the 
> default function is for the relay to open when the inverter turns off. 
> AC voltage on the load side of the breaker does not close the relay 
> and turn the inverter back on automatically.
>
>
> Jason Szumlanski
> Principal Solar Designer | Florida Solar Design Group
> NABCEP Certified Solar Professional (PVIP)
> Florida State Certified Solar Contractor CVC56956
> Florida Certified Electrical Contractor EC13013208
>
>
> On Mon, May 12, 2025 at 9:49 AM Dave Angelini Offgrid Solar via 
> RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>
>     All sounds wrong to me. Call Midnite.
>     Typically there is a AC bypass mechanical switch that allows the
>     gen to bypass the inverter and power loads.
>
>       
>
>     *Dave Angelini Offgrid Solar "we go where powerlines don't"
>     <http://members.sti.net/offgridsolar/>https://offgridsolar1.com/
>     <https://offgridsolar1.com/><http://members.sti.net/offgridsolar/>
>     e-mail offgridsolar at sti.net text 209 813 0060*
>
>
>     On 2025-05-12 9:29 am, Jason Szumlanski via RE-wrenches wrote:
>
>>     Maybe I'm missing something, but it seems like there is a flaw in
>>     the logic for how generator integration works with this
>>     product. Unlike some of the other AIOs, you can't put the
>>     generator on the Grid input in an off-grid scenario. You have to
>>     use the Generator smart load breaker, which isn't a dedicated
>>     generator input, but a programmable circuit. This is problematic
>>     because it seemingly has a normally open internal relay that
>>     closes only when the inverter is ON. At least, that's how it
>>     seems to work in my limited experience.
>>     Why is this a problem? If the battery capacity drops below the
>>     low voltage cutoff, the inverter turns off. You have to turn the
>>     inverter ON for the generator relay to close so you can charge
>>     the battery, but since the battery is too low, the inverter won't
>>     turn on. You would have to reprogram the inverter to drop the
>>     cutoff voltage/SOC below the current battery state. For people
>>     who do not want to use AGS, or if AGS fails to start the
>>     generator for any reason, getting the generator to charge the
>>     battery manually is no easy task.
>>     Moreover, turning the generator on manually when the inverter is
>>     in an OFF state will not pass power to the loads, and will not
>>     turn the inverter ON automatically. You have to get the inverter
>>     turned ON somehow so that the generator power can pass through to
>>     the loads. And since the startup sequence for this inverter is
>>     very quirky, non-intuitive, and unreliable, that makes the
>>     problem even worse. I'm not sure if you can even turn the
>>     inverter ON when there is generator input and the battery is too
>>     low. I don't think you can because the relay is open and the
>>     inverter doesn't even see generator voltage when it is in an OFF
>>     state.
>>     This seems like a serious oversight and a reason to go with one
>>     of the other AIOs on the market. I believe the Sol-Ark 15K and
>>     EG4 18kPV will both immediately power loads and start charging
>>     when the generator is on, regardless of whether the generator is
>>     connected to the Grid or Generator input. Any AC input
>>     immediately passes through to the loads. This is because those
>>     inverters stay "on" when a low battery condition is met, and they
>>     simply stop using the battery to invert power if the battery
>>     conditions do not allow it, based on the settings.
>>     The logic of the Midnite AIOs turning "off" when battery cutoff
>>     is met and opening the generator relay doesn't make sense to me.
>>     Am I wrong about how this works?
>>     Jason Szumlanski
>>     Principal Solar Designer
>>     Florida Solar Design Group
>>
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